Optical display module companies with Lumus as representative have developed an augmented reality optical system based on a stacked array of waveguide structures, wherein a light beam is expanded by the stacked array of waveguide structures in one dimension, whereas in another dimension, an eyepiece with a relatively large aperture is employed to implement transformation of a point-source image of a two-dimensional pixelated image source into a quasi-parallel light beam, thereby ensuring a reasonable exit pupil. However, volumes of the eyepiece and the image source impose extreme limitations on lightening and thinning of the optical display module.
A microelectromechanical system (MEMS) device (e.g., a MEMS micro-mirror) is a new type of control device for light beams, which allows an angular deflection of a light beam around a fixed point and has characteristics such as being compact. Thereby, it has become a display device which has a promising application prospect. Moreover, the scanning light beam emitted from a MEMS micro-mirror is approximately parallel light, which is close to fulfill the requirements for the stacked array of waveguide structures. Therefore, with a combination of the MEMS micro-mirror and the stacked array of waveguide structures, it is easy to lighten and thin the optical display module. However, since the scanning light beam emitted from the MEMS micro-mirror is relatively narrow, there will be problems, such as being difficult for observation when it is directly applied in the stacked array of waveguide structures.
In view of above, how to expand scanning light beams emitted from MEMS micro-mirrors in width and then facilitate its combination with the stacked array of waveguide structure, thereby lightening and thinning the optical display module, is one of those technical problems that is required to be solved urgently at present by those skilled in the art.